Question

how can i determine if the potential difference across each component (e.g voltage and resistor) and is positive or negative?

Answer 1

well generally potential difference is positive because if there is a difference there will be flow of current and current always flow from high to low potential , now if you got the answer as negative that means you point of reference is reverse and due to that you are having negative potential difference, pragmatically PD cant be negative.

Answer 2

if negative PD is negative that means your points of assumption are opposite